Reversing apparatus for furnaces



G. A. MERKT REVERSING APPARATUS FOR FURNAGES Filed March 22. 1937 FTQ 4 v /NvENToR GUSTAV A- MERKT www@ A-rToRN EY l Ul Patented Oct. 3, 1939 I UNITED STATES PATENT OFFICE Morgan Construction Company,

Worcester,

Mass., a corporation of Massachusetts Application March 22, 1937, Serial No. 132,261

6 Claims.

This invention relates to reversing Vapparatus for furnaces, and more particularly to apparatus for use with furnaces of' the type having a pair of regenerators, one of which is being heated by the waste gases while the other is giving up heat to the combustion air.

It is customary to utilize a separate ejector device for each regenerator passage, and to provide means for supplying air to each device under pressure, the air which enters one device serving to entrain and eject the waste gases from the corresponding passage, while the air which enters the other device is directed into the furnace and used for combustion purposes. Heretofore it has been the common practice to supply each ejector device alternately with ejection air and combustion air through a single duct, and since the quantity of ejection air required is usually different from the quantity of combustion air required, the velocity in the duct must be changed whenever the furnace is reversed. This has necessitated the provision of complicated apparatus even when the air flow is to be controlled manually, and has rendered it extremely difhcult to employ automatic regulators for controlling the rate of air delivery. In order to overcome these difculties it has been proposed to employ a four-way valve mechanism having two inlet ducts for ejection air and combustion air respectively and two outlet ducts leading to the respective ejector devices. Such a construction is very bulky and expensive, and cannot be installed in the limited space available in many plants.

It is accordingly one object of the invention to provide a comparatively simple and inexpensive apparatus for supplying air to a pair of ejector devices associated with the regenerator passages of a reversible furnace.

It is a further object of the invention to provide a comparatively simple and inexpensive apparatus for supplying ejection and combustion air to a pair of ejector devices associated with the regenerator passages of a reversible furnace, and particularly to provide apparatus of this type which will be of compact construction and so arranged that the air ilow can be regulated in an eliicient manner.

With these and other objects in View, as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.

In accordance with my invention in its preferred form I provide two ejector devices which are connected to the two regenerator passages of a reversible furnace. Separate conduits are provided for the ejection air and the combustion air, and each conduit has two outlets which communicate with the two ejector devices respectively. Reversible valve means is provided `to close one (Cl. 15S-7.5)

outlet in each pair. Each ejector device is provided with means to direct the air received thereby from the combustion air conduit inwardly through the corresponding regenerator to the furnace. The two conduits are preferably formed by means of a duct having a longitudinal partition mounted therein, and the valve means preferably comprises a pair of interconnected gates arranged for sliding movement to opposite sides of the partition.

Referring to the drawing illustrating one em,- bodiment of the invention and in which like reference numerals indicate like parts,

Fig. 1 is a section through a portion of a regenerative furnace and associated apparatus, the section being taken on the line I-I of Fig. 3;

Fig. 2 is a plan view of the apparatus shown in Fig. 1;

Fig. 3 is a section on the line 3--3 of Fig. 1; and

Fig. 4 is an enlarged view of a portion of Fig. 3.

The embodiment illustrated comprises a furnace III being a combustion chamber I I arranged to be fired with a suitable fuel, such as gas or oil, by means of two burners I2, I2. These burners are connected to a main fuel supply pipe I4 by means of a 3way valve I5 so arranged that the fuel may be directed to the burners alternately. A pair of regenerator passages I6, I6 communicate at their inner ends with the combustion chamber adjacent the respective burners, these passages being provided with suitable checker brick I8.

At the outer end of the passage I6 there is provided an ejector device I9 comprising a vertical upwardly contracting sleeve 20 communicating at its lower end with the passage I6 and enclosed in a casing 22 which connects with a tube or stack 23 located directly above the sleeve. The tube 23 is provided with a valve or damper 24 having an operating arm 25. At the outer end of the passage IIi there is provided a similar ejector device I9 comprising a sleeve 20', a casing 22', a tube 23, a damper 24', and a damper operating arm 25. Air is supplied under pressure to the casing 22, 22', and the construction is such that when this air is to be used for ejection purposes the tube damper will be open and the air will fiow upwardly past the upper end of the sleeve and thence upwardly through the tube, thus creating a suction in thesleeve which withdraws waste gases from the passage therebeneath and by entraining these gases ejects them from the tube. If, on the other hand, the air is to be used for combustion the tube damper will be closed and the air will flow downwardly through the sleeve and through the passage therebeneath to the combustion chamber II where it supports the combustion of the fuel. It will of course be understood the waste gases will give up heat to the checker brick in one passage while the combustion air is absorbing heat from the checker brick in the other passage.

In order to supply the air I preferably provide two separate conduits for the ejection air and the combustion air respectively, and I connect each of these conduits to both of the casings 22, For this purpose I prefer to utilize a single duct 21 to one end of which air is supplied by means of a suitable fan 2S driven by an electric motor 29. The other end of the duct isbranched laterally to connect with both casings 22, 22. This duct 21 is divided longitudinally by means of `a parttion wall 3l into a conduitf32` vfor combustion air and a conduit 33 for ejection air. In the embodiment illustrated the partition 3| is arranged horizontally., with the conduit 32 located above the conduit 33. i

A suitable reversible valve mechanism. is provided to direct all of' the air from the conduit 32 into one of the casings 22., 22', and all of the air from the conduit 33 into the other casing. For this purpose I have shown a pair of vertically slidable gates 35, 35 (Fig. 3) associated with the duct 21 at its connection with the casings 22, 22 respectively. These gates are connected by rods 36, 33 to the opposite end portions of a horizontal lever 31 which 'is fulcruined centrally on a bracket 38 mounted on the top of the duct 21. The ends of the lever 31 are preferably connected by means of rods 43, 40 to the damper operating arms 25, 25 respectively. The lever 31 is arranged to be rocked about its fulcrum by any suitable means, such as a hydraulic motor 4I (Fig. 3).. These various parts are so constructed and arranged that with the lever 31 in the position shown in Fig. 3 the damper 24 will be closed and the damper 24 open. At the same time the gate 35 will be lowered to prevent communication between the casing 22 and the ejection air conduit 33, while the gate 35 will be raised to prevent communication between the casing 22 and the combustion air conduit 32. By rocking the lever 31 the gate 35 can be raised and the gate 35 lowered,

at the same time opening the damper 24 and closing the damper 247. This will reverse the flow lthrough the regenerator passages I6, I3.

The rate of air flow in the ejection air conduit 33 is controlled by means of a damper 43 having an operating arm 44, and this damper is preferably regulated automatically to maintain a substantially constant pressure (usually atmospheric or slightly lower) in the combustion chamber I I. For this purpose I have shown a regulator 45 of the type shown in the United States patent to Temple No. 1,992,048. This regulator comprises a pilot valve mechanism 41 supplied with fluid under pressure from any suitable source by a pipe 43 and connected by tubes 43 with a hydraulic motor 53 which is connected to the operating arm 440i the damper 43.- The pilot valve mechanism 41 is actuated by a lever 52 (Fig. l) which is controlled by a flexible pressure-responsive diaphragm 53 loadedby means of a tension spring 54. The spring is connected at its upper end to a nut 56 carried by a vertical adjusting screw 51. The spring tension` can be adjusted by rotating this screw manually. The space beneath the diaphragm 53 is connected to the combustion chamber I I by means `of a pipe 58. With this arrangement a substantially constant predetermined pressure will be maintained in the combustion chamber I I, for if this pressure varies even slightly it will causea movement-of the diaphragm 53 and the pilot valvemechanism 41, whereupon the motor-50 will-adjust the damper 43 to vary the flow of ejection air and restore the desired pressure.

The rate of air iiow in the combustion air conduit 32 is controlled by means of a damper 6U having an operating armA 6I, and this damper ispreferably regulated automatically to Vary the iiow of combustion air in accordance with variations in the flow of fuel to the furnace. For this purpose I have shown a regulator 62 of the type shown in the United States patent to Temple No. 2,064,864. 'I'his regulator comprises a pilot valve mechanism 64 supplied with fluid under pressure from any suitable source by a pipe 65 and connected by tubes 65 with a hydraulic motor 31 which is connected to. the operating arm 6I of the damper 60. The pilot valve mechanism 64 is actuated by a lever 39 (Fig. l) which is controlled by a pair of connected flexible pressureresponsive diaphragms l@ and 1I. The weight of these diaphragms and associated parts is balanced by a tension spring 13 which is attached at its upper end to a nut 14 carried by a vertical adjusting screw 15. The spring tension can be adjusted by rotating this screw manually.

The diaphragms 13 and 1I are subjected to fluid pressures which vary respectively with the flow of the combustion air and with the ow of the fuel- As illustrated particularly in Fig. l, the combustion air conduit 32 is provided with an orice plate 11. A pipe 18 connects the conduit anterior to the orifice plate with the space above the diaphragm 1-3, and a pipe 19 connects the conduit posterior to the orifice plate with the space beneath the diaphragm 13. A pipe 83 connects the vfuel supply pipe i4 with the space beneath the diaphragm 1 I. With this arrangement the forces on the diaphragms will normally balance, and the motor 61 will hold the damper 6D in the proper position to deliver the combustion air at the correct rate for the amount of fuel being burned. If the rate of fuel supply is changed, however, the-fuel pressure transmitted through the pipe 83 will-change, throwing the regulator 62 momentarily-out of balance. 'Ihis will actuate the pilot valve mechanism 64 and cause the motor'61 toadjust the damper 63 until the resultant change in air flow alters the differential pressure transmitted by the pipes 18 and 19-sufciently to restore balanced conditions in the regulator. Thus the fuel and air supplies are maintained in a predetermined ratio.

It will now be apparent that with the parts in the positions shown in the drawing, gate 35 being lowered, gate 35 raised, damper 24 closed, and damper 24 open, all the air from the combustion air conduit 32 will flow into. the casing 22 and thence through the nozzle 23 and passage I 6, absorbing heat from the hot checker brick I3 and thereafter entering the combustion chamber I I to support the combustion of the fuel supplied by the burner I2. At the same time all the air from the ejection air conduit 33 will flow into the casing 22 and thence upwardly through the tube 23', causing a suction in the nozzle 20 which will withdraw the gaseous products of combustion from the combustion chamber I I through thev passage I 6 and eject them from the tube 23. In traveling through the passage I3 these gases will give up heat tothe checker brick therein. If now the lever 31 is rocked in a clockwise direction in Fig. 3 by means of the motor 4I, and the valve I is turned to direct the fuel to the burner I2', the flow through the furnace will be reversed. Under these conditions gate 35 will be raisedgate -35 lowered, damper 24 open, and

damper 24 closed. All the air from the combustion air conduit 32 will flow into the casing 22 and thence through the nozzle 20 and passage I6 to the combustion chamber Il, this air being heated by the checker brick on its way through the passage I6. At the same time all the air from the ejection air conduit 33 will flow into the casing 22 and thence upwardly through the tube 23, causing a suction in the nozzle 20 which will withdraw the gaseous products of combustion from the combustion chamber Il through the passage I 6 and eject them from the tube 23, These gases will give up heat to the checker brick in the passage I6. Whichever the direction in which the furnace may be operated, the regulator 45 will control the flow of ejection air to maintain a desired pressure in the combustion chamber, and the regulator 62 will control the flow of combustion air to maintain a desired fuel-air ratio.

The apparatus disclosed is comparatively simple and inexpensive to manufacture, and reliable and fool-proof in operation. The air flowing in each of the conduits 32 and 33 is always used for the same purpose, i. e. in conduit 32 for combustion and in conduit 33 for ejection, irrespective of the direction of flow through the furnace. Each of the automatic regulators 45 and 62 can be constructed for one particular function, and will require no adjustment when the furnace is reversed.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. Reversing apparatus for a furnace having a pair of regenerators comprising two ejector devices connected to the regenerators respectively, two parallel conduits extending between the ejector devices and each connected to both ejector devices, a pair of valves spaced apart and each movable from one conduit to the other, means to actuate the valves and cause one valve to close one conduit while the other valve closes the other conduit and vice versa, means to supply ejection air to one conduit and combustion air to the other conduit at points between said valves, and means associated with each ejector device to direct the air received thereby from the combustion air conduit inwardly through the corresponding generator to the furnace.

2. Reversing apparatus for a furnace having a pair of regenerators comprising two ejector devices connected to the regenerators respectively, a duct extending between the ejector devices, a partition dividing the duct into two conduits each of which is connected to both ejector devices, a pair of valves mounted in the duct at spaced points and movable to opposite sides of the partion, means to actuate the valves and cause one valve to close one conduit while the other valve closes the other conduit and vice versa, means to supply ejection air to one conduit and com* bustion air to the other conduit at points between said valves, and means associated with each ejector device to direct the air received thereby from the combustion air conduit inwardly through the corresponding regenerator to the furnace.

3. Reversing apparatus for a furnace having a pair of regenerators comprising two ejector devices connected to the regenerators respectively, a duct extending between the ejector devices, a

partition dividing the duct into two conduits each of which is connected to both ejector devices, a pair of gates mounted in the duct at spaced points and slidable to opposite sides of the partition, means to slide the gates and cause one gate to close one conduit while the other gate closes the other conduit and vice versa, means to supply ejection air to one conduit and combustion air to the other conduit at points between said gates, and means associated with each ejector device to direct the air received thereby from the combusbustion air conduit inwardly through the corresponding regenerator to the furnace.

4. Reversing apparatus for a furnace having a pair of regenerators comprising two upright ejector stacks connected at their lower ends to the regenerators respectively, a horizontal duct connected at its opposite ends with the ejector stacks respectively, a horizontal partition dividing the duct into an upper and a lower conduit each of which communicates with both ejector stacks, a pair of gates mounted in the duct adjacent the ends thereof and slidable vertically to opposite sides of the partition, means to slide the gates and cause one gate to close the lower conduit while the other gate closes the upper conduit and vice versa, means to supply ejection air to one conduit and combustion air to the other conduit, and means associated with each ejector stack to direct the air received thereby from the combustion air conduit inwardly through the correspending regenerator to the furnace.

5. Reversing apparatus for a furnace having a pair of regenerators comprising two ejector devices connected to the regenerators respectively, a duct having two lateral branches which lead to the ejector devices respectively, a partition dividing the duct into two laterally branched conduits each of which is connected to both ejector devices, a gate mounted in each branch of the duct and slidable to opposite sides of the partition, means to slide the gates and cause one gate to close one branch cf one conduit while the other gate closes the other branch of the other conduit and vice versa, means to supply ejection air to one conduit and combustion air to the other conduit, and means associated with each ejector device to direct the air received thereby from the combustion air conduit inwardly through the corresponding regenerator to the furnace.

G. Reversing apparatus for a furnace having a pair of regenerators comprising two ejector devices ccnnected to the regenerators respectively, a duct extending between the ejector devices, a partition dividing the duct into two conduits each of which is connected to both ejector devices, a pair of gates mounted in the duct at spaced points and slidable to opposite sides of the partition, a lever, means connecting the opposite end portions of the lever to the gates respectively, a fulcrum supporting the lever intermediate its length, means to actuate the lever and thereby slide the gates to cause one gate to close one conduit while the other gate closes the other conduit and vice versa, means to supply ejection air to one conduit and combustion air to the other conduit at points between said gates, and means associated with each ejector device to direct the air received thereby from the combustion air conduit inwardly through the corresponding regenerator to the furnace.

GUSTAV A. MERKT. 

